QUESTION: I have a saddle horse that is 9 years old. I have owned her for 5 years. The last 4 years when her pasture gets eaten down, she starts to strip the bark off of the trees. I have tried bitter tasting stuff on the trees but it doesn't stop her. Why is she doing this and what can I do about it?

ANSWER: First we emailed back and asked if the owner was supplementing this horse with roughage once the pasture became Non Sufficient to meet it's daily feed requirements. Usually Hay but sometimes Cubes to determine if the horse was being fed a roughage. Feeding grain is not roughage which some people feed instead without thinking??? Then the horse is forced to eat anything from inedible weeds to trees in order to survive.
Some Weeds, Shrubs and Trees can be highly Toxic to horse when consumed in to great of quantity. Just ONE species of tree is
Black Walnut ("Juglans Nigra" is the Scientific Name). Most cases of Toxicity have taken place when people used wood shavings for bedding containing a percentage of Black Walnut. Within 24 hours of a horse being exposed to these shavings, they become reluctant to move, are depressed, increase in temperature, pulse and respiration. Increase of abdominal sound. Increased heat (temperature) of the hoof, (felt on the Coronet Band). Limb Edema (swelling of the legs with fluid). Lameness.
With continued exposure, Severe Laminitis (Founder). Of course eating leaves, bark or new growth off of a live tree results in the same.

Also some Weeds are also highly Toxic causing Colic, Founder or again like some Tree Barks, Liver Failure or Kidney Disease. Also some Ornamental Shrubs. Some Reactions are immediate, some take a lot of time for the Toxins to build up in the horses system.

Also ingesting large amounts of Tree Bark can cause deadly "Impaction Colic" as the bark does not absorb enough liquid from the horses Digestive Tract to make the Stool normal instead of a Hard, Dry Matter that does not exit the bowel correctly. ) Hopefully the horse is just stripping the Bark off and dropping it on the ground. Not actually swallowing it?

Since the owner did not speak of Failing Health in the horse and it is being fed roughage then...............................................

The usual reason for a horse doing this is sheer "Boredom". When there is some grass to nibble on and/or roughage in front of them at all times they stay away from nibbling on trees, etc. This is often a "Learned Behaviour" and may have taken place before you owned the horse. Perhaps at one time (OR NOW) the horse was/is confined to, too small of a space and out of Boredom began doing this? Horses require a sufficient amount of SPACE to be happy in. Preferably with another horse for companionship or at least some other large animal(s) such as Cattle, Llamas, Donkeys, even Goats or Sheep. Horses are HERD ANIMALS and usually do best with something in the pasture with them. Preferably another Equine if possible.

Just some Behavioural problems seen in horses Confined with no avenue to prevent Mental Boredom are Stall Weaving, Stall Walking, Chewing on Inedible things such as rubber, plastic items, etc., Excessive Pawing, Excessive Head Bobbing, and the most common one is CRIBBING on anything they can sink their teeth onto. Usually wooden items.

Such Abnormal Mental Behaviours once learned by the horse can sometimes be "Permanent". I have a document on Cribbing under the OUR ARCHIVES section of my website for people to view. Of course, the main thing is to turn the horse Out in a pasture (not pen) of sufficient size to prevent the need to Crib since it is then able to move around and be in a more Natural Horse Environment free of the Mental stress of Boring Confinement........................................ NOTE: For all these Behavioural Problems listed above, get that horse out into a decent size field or pasture. No more small pen or stall!!! And also give the horse something to do for exercise on a regular DAILY basis. Something OUTSIDE to do if confined to a stall inside.............. Daily for sufficient time each day.

That said, the final reasons are:

Some horses with Mineral Deficiencies (or an imbalance of Minerals being fed to them) or even perhaps lacking good old Salt will fixate on something and begin eating it. Anything from Dirt to Tree Bark. Plus other items.

Some horses with a Gut Load of worms will do the same. And NO, deworming only once or twice a year may not be enough for your horse. The best way to know is take Fresh Fecal Samples (Stool Samples) to your Vet to determine if your deworming schedule is right for your horse(s).

And one is just plain STRESS. Some horses under continued Stress will resort to Abnormal Behaviour including eating Abnormal items even if correctly fed. Mental or Physical Stress. Only the Horse Owner themselves will be able to figure out what that Mental Stress or what pain from a Physical problem might be. Or someone who can watch the horse in person and/or knows the horse.

Often a companion Horse cures the problem if just BORED.

Last........................ I have yet to find a product to apply to trees to stop this!!! In order to protect the Trees if it is just the trunks of the trees being stripped of bark, the only way I have found is to fence the trees off or if unable to do that, then wrapping the trunks with plain old "Chicken Wire" or something else suitable. Many people don't want to watch their trees eventually die from being stripped of their bark. Others want to protect their horses health. Thank You.